The unprecedented reaction of dimethylsulfonium methylide with Michael acceptors: Synthesis of 1-substituted vinyl silanes and styrenes

Article abstract of DOI:10.1039/b509102k

Rather than the usual cyclopropanation, conditions for an unprecedented elimination reaction from the adduct of dimethylsulfonium methylide and various Michael acceptors have been established leading to functionalized 1-substituted alkenes. In silyl substituted substrates (2a and 2h), where a facile Peterson-type olefination is possible from the adduct; elimination took place instead to give functionalized 1 -substituted vinyl silanes. Aryl substituted Michael acceptors (2b-e, 2g and 2i-k) also underwent a similar kind of olefination to give 1-substituted styrene derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for olefination vs. demethylation increases as the aryl substituent becomes more electron deficient. Alkylidene malonates (2f and 2l) with a β-alkyl substituent did not favour the olefination process. Sequential addition of Michael acceptors and alkyl halides to a mixture of dimethylsulfonium methylide and sodium dimsylate provided olefination followed by alkylation on the active methine group. A mechanistic pathway has been formulated from the studies of a few sulfonium methylides. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b509102k

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A R T I C L E
The unprecedented reaction of dimethylsulfonium methylide with
Michael acceptors: synthesis of 1-substituted vinyl
silanes and styrenes†
Sonali M. Date, Rekha Singh and Sunil K. Ghosh*
Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
E-mail: ghsunil@magnum.barc.ernet.in
Received 27th June 2005, Accepted 20th July 2005
First published as an Advance Article on the web 15th August 2005
Rather than the usual cyclopropanation, conditions for an unprecedented elimination reaction from the adduct of
dimethylsulfonium methylide and various Michael acceptors have been established leading to functionalized
1-substituted alkenes. In silyl substituted substrates (2a and 2h), where a facile Peterson-type olefination is possible
from the adduct; elimination took place instead to give functionalized 1-substituted vinyl silanes. Aryl substituted
Michael acceptors (2b–e, 2g and 2i–k) also underwent a similar kind of olefination to give 1-substituted styrene
derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the
adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for
olefination vs. demethylation increases as the aryl substituent becomes more electron deficient. Alkylidene malonates
(2f and 2l) with a b-alkyl substituent did not favour the olefination process. Sequential addition of Michael acceptors
and alkyl halides to a mixture of dimethylsulfonium methylide and sodium dimsylate provided olefination followed
by alkylation on the active methine group. A mechanistic pathway has been formulated from the studies of a few
sulfonium methylides.
olefin 6 (path ‘c’). The formation of cyclopropane 4 has been well
Introduction
studied while that of olefin 5 or 6 has not been observed. This
The Corey–Chaykovsky reagent, dimethylsulfonium methylide
paper details the development of specific reaction conditions and
1, generated from a trimethylsulfonium salt and a base is known
to react with an aldehyde or a ketone to give an epoxide by
selection of the substituents (R, E1 and E2) on 2 for the formation
of 5. In addition, a one-pot sequential olefination–alkylation
an overall methylene insertion.1 Excess reagent could lead to
protocol was devised by quenching the reaction with various
the formation of allylic alcohol by further addition of the
alkyl halides leading to functionalised 1-substituted olefins. A
ylide on the epoxide.2 In line with the carbonyl compounds,
mechanistic pathway has also been formulated from studies of
imines give aziridines with 1.1 The ylide can be used for the
a few sulfonium methylides. A communication4 on a part of this
conversion of halides and mesylates to one-carbon homologated
work has already been published.
terminal alkenes.3 It has been commonly used to add on Michael
acceptors in a 1,4-fashion to provide cyclopropanes.1 Thus, the
Results and discussion
reaction of ylide 1 with the Michael acceptor 2 gives a betaine
intermediate 3 which in principle can undergo various reactions
(Scheme 1), the driving force in all cases being the elimination
of Me2S. The most well known amongst these is the formation
of cyclopropane 4 (path ‘a’, Scheme 1). The other possible mode
of reaction which could be envisioned from intermediate 3 is
the loss of a proton and Me2S in the presence of excess base
resulting in the formation of an olefin 5 (path ‘b’). An additional
possibility, Peterson-type olefination is plausible in the case of
substrates with the R group being a silyl substituent leading to
Recently, we have developed a method for the preparation of
the 2-silyl alkylidene malonate 2a by a high yielding reaction of
PhMe2SiLi with diethyl ethoxymethylenemalonate (Scheme 2)
and used it as a Michael acceptor in the preparation of a
functionalised b-silyl ketone.5 When 2a was reacted with 1,
generated from Me3SI1 and sodium dimsylate (1 equiv) in
DMSO–THF (70 : 30) at 0 ◦C, we obtained the anticipated
product, cyclopropane 4a (Table 1; entry 1) in moderate yield.
Remarkably, when the amount of base was increased (1.5 equiv),
the formation of vinyl silane 5a was also found in addition to
cyclopropane 4a (entry 2). The formation of 5a was highly
dependent upon the number of equivalents of base present
as shown in Table 1. The solvent composition also has a
significant effect in product selectivity (Table 1; entries 2, 4–
6) besides improving the combined yield (entries 3 and 8). The
best condition for the olefination was to use a combination of
DMSO–THF (30 : 70) and 2.5 equivalents of sodium dimsylate
in addition to 1.2 equivalents of Me3SI. Under these conditions
(Table 1; entry 8), 5a was isolated in 66% yield. It was also
gratifying to note that 5a was formed exclusively from the
adduct 3 (Scheme 1; R = PhMe2Si, E1 = E2 = CO2Et) where
Scheme 1
† Dedicated to Professor Ian Fleming F. R. S. of Cambridge University
on his 70th birthday.
Scheme 2
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8
3 3 6 9
©

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Table 1 Effect of solvent and base on selectivity (cyclopropanation/
olefination)
cases. When 2-alkylidene malonate 2f was subjected to the same
reaction conditions, desired product was not formed; instead,
methylated isomerised product 7 was obtained in 37% yield
(Scheme 4).
Entry
DMSO–THF
Equiv basea
4a–5ab
Yield (%)c
1
2
3
4
5
6
7
8
70 : 30
70 : 30
70 : 30
60 : 40
40 : 60
30 : 70
30 : 70
30 : 70
1.0
1.5
2.5
1.5
1.5
1.5
1.0
2.5
100 : 0
98 : 2
0 : 100 27
96 : 4
87 : 13
76 : 24
100 : 0
55
40
Scheme 4
51
55
60
36
Our next interest was to study the influence of activating
groups present in the Michael acceptor 2 on olefination reaction.
The substrate with a phosphonate activating group 2g upon
olefination–methylation gave exclusively the desired styrene
derivative 5k in 50% yield (Table 3). The silyl substituted
alkylidene cyanoacetate 2h when subjected to similar conditions
gave exclusively the desired vinyl silane 5l (Table 3). Contrary to
silyl substitution, the arylidene cyanoacetate 2i gave the desired
product 5m along with a double methylation product 8 in a ratio
of 6 : 4. The cis-relationship between the Me and the Ar in
8 was confirmed by 1D-NOE study (7.5% NOE enhancement
was observed between the olefinic proton and the C-1 Me). The
selectivity (5m vs. 8) could not be improved by changing the
cation from Na to K. Fortunately, the reaction could be driven
in the desired direction to give styrene 5m albeit in poor yield by
0 : 100 66
a Equivalent with respect to Me3SI. b Ratio determined by GC.
c Combined isolated yield of 4a and 5a.
the elimination of a proton and dimethylsulfide was favored
over the loss of a silyl group in a Peterson-type elimination. In
addition, a one-pot olefination–alkylation protocol was devised
using 1.2 equivalents of Me3SI and 2.5 equivalents of sodium
dimsylate, and quenching the reaction with alkyl halides leading
to functionalised vinyl silanes 5b–f in good yields as shown
in Scheme 3. It is worth mentioning that these types of vinyl
silanes are important intermediates in organic syntheses6–11 and
there has been no reported general access to 1-substituted vinyl
silanes.12
13
the addition of MgBr2 into the reaction medium prior to the
addition of methyl iodide.
Even though the stabilized allylic anion 9 (Scheme 5) could
provide two regioisomeric alkylation products, 5 by a-alkylation
and 10 by c-alkylation; the present olefination–alkylation pro-
tocol using malonates exclusively gave the a-alkylated products
5b–5l. Base induced c-deprotonation in alkylidene malonates
and cyanoacetates followed by alkylation exclusively at the a-
position has been documented by Cope and co-workers.14 We
were therefore inquisitive to know whether the same level of re-
gioselectivity would be obtained upon olefination–protonation
instead of alkylation; although in the case of silylated substrate
2a, the protonation exclusively took place at the a-position to
give 5a (Table 1).
Scheme 3
At this stage we were not convinced whether the silyl
(PhMe2Si) substitution in 2a was responsible for this preferred
elimination over cyclopropanation. Therefore, this one-pot
protocol (olefination–alkylation) was attempted using a series
of arylidene malonates 2b–e. We were pleased to observe that
the above elimination process was general and furnished the
styrene derivatives 5g–i exclusively in moderate to good yields
as shown in Table 2. The poor yield of the styrene 5j could
be due to the degradation of the substrate as well as the
product under the reaction conditions as was evident from the
generation of a substantial amount of colored polar material.
No cyclopropanation product was observed in any of these
Table 2 Preparation of substituted styrenes
Scheme 5
Therefore, this olefination was attempted with a series of
2-substituted arylidene malonates 2b–e and 2j–k. Indeed we
observed a very high level of selectivity for a-protonation
and not a trace amount of c-protonated product was formed.
Unexpectedly, in addition to the olefination products 5n–s, small
amounts of side products 11b–e and 11j–k were also formed
(Table 4). When 2-alkylidene malonate 2l was subjected to the
same reaction conditions, instead of the desired olefination,
product 12 was formed due to isomerization of the starting
material along with the thiomethylmethyl addition product 11l
(Scheme 6).
Entry
Ar
Substrate
Product
Yield (%)
1
2
3
4
Ph
2b
2c
2d
2e
5g
5h
5i
73
57
69
20
4-MeO–C6H4
4-Br–C6H4
4-NO2–C6H4
5j
3 3 7 0
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8

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Table 3 Effect of activating group on the one-pot olefination–alkylation reaction
Entry
X
R
Substrate
Product(s)
5m/8
Yield (%)
1
2
3
4
5
P(O)(OEt)2
CN
CN
CN
CN
4-MeO–C6H4–
PhMe2Si–
4-MeO–C6H4–
4-MeO–C6H4–
4-MeO–C6H4–
2g
2h
2i
5k
—
—
64 : 36
65 : 35
100 : 0
50
28
5l
5m; 8
5m; 8
5m; 8
60
2i
55a
17b
2i
a Potassium dimsylate was used instead of sodium dimsylate. b MgBr2 was added prior to the addition of MeI.
Table 4 Effect of aryl substituent on olefination
Entry
Ar
Substrate
5/11a
Product 5 (% yield)
Product 11 (% yield)
r
log(selAr/selPh)
1
2
3
4
5
6
Ph
2b
2c
2d
2e
2j
77 : 23
70 : 30
82 : 18
82 : 18
80 : 20
85 : 15
5n (65)
5o (61)
5p (68)
5q (46)
5r (68)
5s (70)
11b (15)
11c (20)
11d (7)
11e (8)
11j (11)
11k (8)
0
0
4-MeO–C6H4–
4-Br–C6H4–
4-NO2–C6H4–
3-MeO–C6H4–
3-Cl–C6H4–
−0.268
0.232
0.778
0.115
0.373
−0.157
0.134
0.134
0.077
0.228
2k
a Ratio determined from crude product by 1H NMR.
Scheme 6
The formation of products 11 from 2 via intermediate 3
(Scheme 1) could be rationalized as follows. Abstraction of
a proton (path b, Scheme 1) by sodium dimsylate followed
by loss of Me2S results in the formation of olefins 5. A
nucleophilic attack of Na-dimsylate on the methyl group of
the dimethylsulfonium substituent in an intermediate of type
3 competes with proton abstraction resulting in the formation
of products 11 (Table 4). To gain insight into the electronic
dependence of the selectivity of olefination vs. demethylation
from intermediate 3, a Hammett plot15 (Fig. 1) was constructed
by plotting the log of the selectivity (olefination/demethylation)
ratios vs. r with the results obtained from a few arylidene
malonates (Table 4); where the aryl ring embodied substituents
having Hammett values in the range of −0.3 ≤ r ≤ 0.8. Detailed
examination of the selectivities of olefination i.e. the ratio of
olefination product 5 to demethylation product 11 for electron-
rich and electron-poor arylidene malonates revealed a clear
trend in selectivity. Taking an unsubstituted phenyl ring as a
reference point, the selectivity increased as the aryl ring became
more and more electron poor. The plot was linear over the entire
domain of tested compounds (q ≈ 0.6, R2 = 0.999) with the
exception of 4-NO2 (r = 0.778), where a significant deviation
was found. The positive slope of the Hammett plot is indicative
that an electron withdrawing aryl ring improves olefination. A
Fig. 1 Hammett correlation of the log of relative selectivity for
olefination versus Hammett value, r (taken from ref. 15).
possible explanation for the improved rates of olefination of
arylidene malonates where the aryl substituent is embodied with
electron-withdrawing groups is that these substituents lower
the pKa of the benzylic protons in intermediate 3, effectively
increasing the ease of proton abstraction by a base. The aryl
ring with 4-NO2 substitution followed the same trend although
the magnitude was much less than expected. This anomaly is due
to the degradation of the substrate as well as the products under
the reaction conditions as reflected in the isolated yields. In the
case of 2-alkylidene malonate 2l, no olefination product was
observed. The intermediate of type 3 generated after conjugate
addition of dimethylsulfonium methylide to 2l is unable to
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8
3 3 7 1

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undergo a proton loss due to the high pKa of its b-proton.
Instead, loss of a methyl group from the dimethylsulfonium
substituent by nucleophilic attack of dimsylate resulted in the
formation of 11l (Scheme 6). In the case of 2-silylalkylidene
malonate 2a, the exclusive formation of olefination product 5a
(Table 1, entry 8) could be attributed to a much easier loss of the
CH proton a to the SiMe2Ph group.
occurs first by Michael addition of a carbanion on an elec-
trophilic alkene, followed by abstraction of the vinylic proton
by excess base and b-elimination of the leaving group leading
to an allylic anion which on protonation provides the olefinic
product. This kind of reaction does not take place in the case of
arylidene malonates, instead normal Michael addition products
were isolated. In some specific cases, this overall substitution
process goes via cyclization leading to a cyclopropane ring which
undergoes ring opening to give the product.
The only exception to exclusive a-methylation was found with
arylidene cyanoacetate 2i as shown in Table 3 (entries 3 and
4). This substrate gave both a-methylation product 5m and c-
methylation product 8 (5m/8 = 65 : 35). In order to probe
the mechanism of the formation of 8, we carried out a few
experiments. First, the arylidene cyanoacetate 2i was subjected
to the optimized conditions for olefination and quenched with
aqueous acid which gave a mixture of desired olefination
product 5t and arylidene cyano acetate 10i (5t/10i = 65 : 35)
predominantly as the E-isomer (E/Z = 78 : 22) (Scheme 7).
The products were separated, individually treated with Na-
dimsylate and quenched with aq. HCl. The olefination product
5t was recovered unchanged whereas pure (E)- or pure (Z)-10i
underwent isomerization to provide a mixture of (E)- and (Z)-
10i (E/Z = 78 : 22) quantitatively. These observations infer that
olefin 5i and olefin 10j are formed independently and are not
interconvertible under the reaction conditions. In addition to
this, olefin 5b also remained unaltered when treated with Na-
dimsylate followed by aqueous or anhydrous acid.
It has also been observed by Fleming et al.17 that b-silylethyl
sulfoxide having a-carbonyl substituent(s) 16 prefers elimination
of the b-hydrogen instead of the silyl group to give the b-silyl
substituted a,b-unsaturated carbonyl compound 17 (Scheme 8).
The reason for this is that silicon stabilizes the alpha carbanion
making the loss of hydrogen more facile as well as the carbonyl
group increasing the electrophilicity of the carbon adjacent to it
and hence a push–pull kind of mechanism operates.
In the present work, the isolation of cyclopropane 4a when
substrate 2a was treated with one equivalent of ylide 1 showed
that it first undergoes a Michael type addition to the activated
olefin 2a to give a reactive intermediate 3 which undergoes rapid
eliminative cyclisation (Scheme 1). This product 4a on treatment
with an excess of sodium dimsylate did not give the olefin 5a,
therefore, precludes its intermediacy in this olefination. The
formation of the olefin 5a when the reaction was carried out
in the presence of excess base (sodium dimsylate) showed that
the base has a significant role in the removal of Ha and Me2S. The
two alternative pathways in the presence of excess base are shown
in Scheme 9. In path ‘a’, analogous to Makosza’s mechanism, the
base takes the proton Ha from 3 with concomitant elimination
of Me2S leading to olefin 5 after alkylation with alkyl halides. In
the second pathway, in parallel with Fleming’s observation, the
base takes a proton from one of the methyl groups attached to
sulfur and generates a new ylide/ylene 18 which then undergoes
cycloelimination of Ha and Me2S to give the olefin 5.
Scheme 7
Plausible pathway for the formation of the 1-substituted olefins
Makosza and Kwast16 have shown that carbanion 13 containing
a leaving group reacts, in the presence of excess base, with
electrophilic alkene 14 giving product 15 in which vinylic
hydrogen is replaced with a carbanion moiety (Scheme 8). It
has been proposed that such vicarious nucleophilic substitution
Scheme 9
The substantial clue supporting pathway ‘b’ came from studies
using different sulfonium methylides. The results are presented
in Scheme 10. The diphenylsulfonium methylide generated in
situ from diphenylmethylsulfonium tetrafluoroborate 19 ‡ in the
presence of excess base on reaction with olefin 2a provided only
cyclopropane 4a. On the contrary, cyclic sulfonium methylides
generated in situ from sulfonium iodides 20 and 21, respectively,
gave the desired olefination product 5b. The former ylide
lacks the protons for generation of an intermediate of type
18 (Scheme 7) after its addition to the activated olefin 2a,
thus only cyclopropanation takes place, whereas the latter cases
‡ This salt did not work well under our standard olefination procedure.
A modified procedure (vide experimental) was therefore introduced.
Under these modified conditions, Me3SI also gave the desired olefination
product 5b when reacted with 2a.
Scheme 8
3 3 7 2
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8

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tetrahydrothiophene and pentamethylene sulfide, respectively,
and standing at room temperature overnight followed by
crystallization from EtOH. The benzyl sulfonium salts 22 and
23 were also prepared by heating a solution of benzyl bromide
and tetrahydrothiophene or pentamethylene sulfide in hexanes
followed by crystallization from EtOH–EtOAc.
1H NMR and 13C NMR spectra were recorded on a Bruker
200 MHz spectrometer. Spectra were referenced to residual
1
chloroform (d 7.26 ppm, H; 77.00 ppm, 13C). Chemical shifts
are reported in ppm (d); multiplicities are indicated by s
(singlet), d (doublet), t (triplet), q (quartet), quint (pentet), m
(multiplet) and br (broad). Coupling constants, J, are reported
in Hertz. Mass spectra were recorded on a Fissons VG Quatro
II mass spectrometer (EI 70 V; CI 30 V). HRMS were recorded
in a Waters Micromass Q-TOF Mass Spectrometer. Infrared
spectra (IR) were recorded on a Nicolet Impact 410 FT IR
spectrophotometer in NaCl cells or in KBr discs. Peaks are
reported in cm−1. Melting points (mp) were determined on a
Fischer John’s melting point apparatus and are uncorrected.
Analytical thin-layer chromatography was performed using
home made Acme silica gel plates (about 0.5 mm).
Scheme 10
have methylenes and readily generate ylides18 of type 18 in the
presence of base thus providing the desired product.
Having established the olefination protocol with dimethylsul-
fonium methylide and various Michael acceptors, we explored
the possibility to extend this methodology for the synthesis of
trisubstituted olefins. We performed this reaction using benzyl
sulfonium salts 22 and 23 with 2a, however no olefination
product 24 was detected. Instead, the generated ylides under-
went a Sommelet–Hauser rearrangement18,19 under the reaction
conditions used to give rearranged products 25 and 26 only
(Scheme 11).
Ethyl (Z)-2-cyano-3-dimethyl(phenyl)silyl-2-propenoate 2h
A solution of ethyl ethoxymethylenecyanoacetate (5.6 gm,
33.3 mmol) in THF (100 cm3) was added to a stirred solution
of dimethyl(phenyl)silyllithium23 (0.95 M solution in THF)
(35 cm3, 33.4 mmol) dropwise at −78 ◦C. After the addition
was over, the reaction mixture was stirred for 15 min and the
cold bath was removed. The reaction mixture was allowed to
attain room temperature (about 25 min) and was then poured
into a saturated ammonium chloride solution and extracted
with Et2O. The organic extract was washed with water and
with brine, dried (MgSO4) and evaporated. The residue was
purified by column chromatography on silica using hexane–
EtOAc (95 : 5) as eluent to give the cyanoester 2h (0.9 g, 24%) as
a colorless oil; Rf 0.57 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1
=
=
3070 (HC C), 2227 (CN), 1732 (CO), 1587 (C C), 1234 (SiMe)
and 1115 (SiAr); dH(200 MHz, CDCl3) 0.64 (6 H, s, 2 × SiMe),
1.36 (3 H, t, J = 7.1 Hz, MeCH2OCO), 4.32 (2 H, q, J =
7.1 Hz, MeCH2OCO), 7.40–7.60 (5 H, m, Ar) and 8.07 (1 H, s,
=
C CHSi); dC(50 MHz, CDCl3) −3.47 (2 C), 14.01, 62.77, 115.30,
Scheme 11
120.74, 128.24 (2 C), 130.14, 133.84 (2 C), 134.42, 160.88 and
163.74; m/z (EI) 259 (M+, 4%), 258 (10), 244 (14), 230 (73), 216
(74), 188 (41.5), 186 (50), 145 (60.4), 137 (45.5), 135 (65.3), 105
(100), 103 (65.3), 91 (32.7), 75 (94).
In conclusion, we have developed a novel application of
dimethylsulfonium methylide for the general preparation of non-
readily accessible and synthetically valuable 1-substituted vinyl
silanes, and styrene derivatives from easily available activated
olefins. The additional feature of these silanes and styrenes is that
they have a b,c-unsaturated diester moiety in their framework
which is not always easy to obtain by other methods. This study
also demonstrated that by varying conditions, the reactions
could be tuned in either direction to give an olefin or cyclo-
propane exclusively. The limitation of this olefination protocol
is that it works with sulfonium methylides only and does not
work for b-alkyl substituted Michael acceptors. The mechanistic
studies on the formation of vinyl silanes and styrenes confirmed
the intermediacy of ylide 18 which underwent cycloelimination
to provide the olefination products.
Diethyl 2-dimethyl(phenyl)silylcyclopropane-1,1-
dicarboxylate 4a
A solution of sodium dimsylate (1 mmol) in DMSO (4 cm3) was
prepared. The solution was diluted with THF (1 cm3) and cooled
to 0 ◦C. Solid trimethylsulfonium iodide (205 mg, 1 mmol)
was introduced into the flask and the reaction mixture was
stirred under the same conditions for 15 min. A solution of 2a
(0.306 gm, 1 mmol) in dry THF (0.75 cm3) was rapidly added to
the reaction mixture. It was slowly brought to room temperature
(about 1 h) and stirred for 1 h. The reaction mixture was diluted
with water and extracted with ether. The organic extract was
washed with brine, dried (MgSO4) and evaporated. The residue
was purified by column chromatography on silica using hexane–
EtOAc (95 : 5) as eluent to give the cyclopropane 4a (173 mg,
55%) (found: C, 63.36; H, 7.88. C17H24O4Si requires C, 63.72; H,
7.55%); Rf 0.32 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1 1731
Experimental
General methods
The ester 2a was prepared following the published procedure.5
Compounds 2b–2f and 2i–l were prepared by standard
Knoevenagel condensation between different aromatic alde-
hydes and diethyl malonate or ethyl cyanoacetate. Ethyl
ethoxymethylenecyanoacetate,20 compound 2g,21 and diphenyl-
=
(C O), 1249 (SiMe) and 1116 (SiPh); dH(200 MHz, CDCl3)
0.25 (3 H, s, SiMe), 0.34 (3 H, s, SiMe), 1.10 (1 H, dd, J = 9.5,
11 Hz, SiCH), 1.18 (3 H, t, J = 7.1 Hz, MeCH2OCO), 1.26 (3
H, t, J = 7 Hz, MeCH2OCO), 1.41 (1 H, dd, J = 3.4, 9.5 Hz,
CHAHBCHSi), 1.52 (1 H, dd, J = 3.4, 11 Hz, CHAHBCHSi),
3.80–4.30 (4 H, m, 2 × MeCH2OCO) and 7.30–7.75 (5 H, m,
Ar); dC(50 MHz, CDCl3) −3.32, −3.16, 13.80, 14.00, 15.35,
methylsulfonium tetrafluoroborate 19 (Ph2SMe+ BF4
)
were
−
22
prepared following the literature procedures. Sulfonium salts
20 and 21 were prepared by mixing excess iodomethane with
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8
3 3 7 3

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18.38, 33.31, 61.16, 61.56, 127.71 (2 C), 129.12, 133.78 (2 C),
137.86, 169.07 and 170.98; m/z (EI) 305 (M+ − Me, 100%), 275
(11), 243 (70.3), 231 (90), 215 (21), 187 (76), 169 (73), 159 (27),
135 (41) and 105 (29).
0.42 (6 H, s, 2 × SiMe), 1.22 (6 H, t, J = 7.1 Hz, 2 ×
MeCH2OCO), 1.59 (3 H, s, MeC(CO2Et)2), 4.04–4.25 (4 H, m,
=
=
2 × MeCH2OCO), 5.61 (1 H, s, SiC CH), 5.82 (1 H, s, SiC CH)
and 7.31–7.58 (5 H, m, Ar); dC(50 MHz, CDCl3) −0.59 (2 C),
13.76 (2 C), 21.84, 59.92, 61.20 (2 C), 127.41 (2 C), 128.61,
129.07, 133.87 (2 C), 139.29, 148.50 and 171.41 (2 C); m/z (EI)
319 (M+ − Me, 100%), 289 (7), 262 (27), 261 (27), 257 (93), 245
(40), 229 (9), 201 (18), 173 (38), 169 (8), 135 (48), 111 (20) and
105 (29).
This compound 5b was also prepared using sulfonium salts
20 and 21 instead of trimethylsulfonium iodide in 67% and 68%
yields, respectively.
This compound was also prepared using diphenylmethyl-
sulfonium tetrafluoroborate (Ph2SMe+ BF4−) (19). For this, a
solution of the sulfonium salt 19 (173 mg, 0.6 mmol, 1.2 equiv)
in THF–DMSO (1 : 1) (1 cm3) was added to a stirred suspension
of sodium hydride (55% in oil) (27 mg, 0.6 mmol, 1.2 equiv)
(freed from oil by washing with dry hexane and dried) in THF
(1.5 cm3) at −78 ◦C. The temperature of the bath was raised
◦
to −50 C, and sodium dimsylate (1 cm3 of a 0.75 M solution
in DMSO, 0.75 mmol, 1.5 equiv) was added into the reaction
mixture followed by a solution of the ester 2a (153 mg, 0.5 mmol,
1 equiv) in dry THF (1 cm3). The reaction mixture was allowed
to attain room temperature and was stirred for 45 min, cooled
on an ice–water bath and MeI (0.16 cm3, 2.5 mmol, 5 equiv) was
added. After 14 h at room temperature, the reaction mixture
was diluted with water and extracted with ether. The organic
extract was washed with brine, dried (MgSO4) and evaporated.
The residue was purified by column chromatography on silica
using hexane–EtOAc (95 : 5) as eluent to give the cyclopropane
4a (140 mg, 88%).
Diethyl (1-dimethyl[phenyl]silylvinyl)ethylmalonate 5c. Pro-
cedure as described for the preparation of 5b; yield 79% (found:
C, 65.22; H, 8.27. C19H28O4Si requires C, 65.48; H, 8.10%); Rf
0.48 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1 1731 (C O), 1244
=
(SiMe) and 1110 (SiPh); dH(200 MHz, CDCl3) 0.43 (6 H, s, 2 ×
SiMe), 0.89 (3 H, t, J = 7.4 Hz, MeCH2), 1.20 (6 H, t, J =
7.1 Hz, 2 × MeCH2OCO), 2.10 (2 H, q, J = 7.4 Hz, MeCH2),
4.11 (2 H, q, J = 7.1 Hz, MeCH2OCO), 4.12 (2 H, q, J = 7.1 Hz,
=
=
MeCH2OCO), 5.67 (1 H, s, SiC CH), 5.91 (1 H, s, SiC CH)
and 7.30–7.58 (5 H, m, Ar); dC(50 MHz, CDCl3) −0.32 (2 C),
9.44, 13.92 (2 C), 28.57, 61.07 (2 C), 63.72, 127.42 (2 C), 128.53,
130.80, 134.02 (2 C), 140.09, 147.52 and 171.00 (2 C); m/z (EI)
333 (M+ − Me, 33%), 303 (5), 275 (16), 271 (59), 259 (13), 233
(12), 215 (32), 187 (42), 159 (87), 153 (48), 135 (100), 141 (33),
125 (46), 121 (22), 107 (20), 105 (71), 95 (38), 91 (30), 77 (33)
and 75 (73).
Diethyl (1-dimethyl[phenyl]silylvinyl)malonate 5a
A solution of sodium dimsylate (2.5 mmol) in DMSO (2.5 cm3)
was prepared. The solution was diluted with THF (4 cm3) and
cooled on an ice–salt bath (−8 ◦C). Solid trimethylsulfonium
iodide (245 mg, 1.2 mmol) was introduced into the flask and
the reaction mixture was stirred under the same conditions
for 15 min. A solution of 2a (0.306 gm, 1 mmol) in dry THF
(2 cm3) was rapidly added to the reaction mixture. It was slowly
brought to room temperature (about 1 h) and stirred for 1 h.
The reaction mixture was diluted with water and extracted
with ether. The organic extract was washed with brine, dried
(MgSO4) and evaporated. The residue was purified by column
chromatography on silica using hexane–EtOAc (95 : 5) as eluent
to give the vinyl silane 5a (210 mg, 66%) (found: C, 63.44; H,
7.90. C17H24O4Si requires C, 63.72; H, 7.55%); Rf 0.30 (hexane–
Diethyl allyl(1-dimethyl[phenyl]silylvinyl)malonate 5d
Procedure as described for the preparation of 5b except 1.5
equiv of allyl bromide were used; yield 60% (found: C, 66.71; H,
8.11. C20H28O4Si requires C, 66.63; H, 7.83%); Rf 0.32 (hexane–
EtOAc, 98 : 2); mmax(neat)/cm−1 1731 (C O), 1245 (SiMe) and
=
1111 (SiPh); dH(200 MHz, CDCl3) 0.42 (6 H, s, 2 × SiMe),
1.19 (6 H, t, J = 7.1 Hz, 2 × MeCH2OCO), 2.82 (2 H, d, J =
=
7.1 Hz, CH2 CHCH2), 3.97–4.19 (4 H, m, 2 × MeCH2OCO),
=
5.00 (1 H, s, CHAHB CHCH2), 5.06 (1 H, d, J = 5 Hz,
=
=
CHAHB CHCH2), 5.68 (1 H, s, SiC CH), 5.68–5.94 (1 H, m,
EtOAc, 95 : 5); mmax(neat)/cm−1 1732 (C O), 1250 (SiMe) and
=
=
=
CHAHB CHCH2), 5.94 (1 H, s, SiC CH) and 7.30–7.57 (5 H,
m, Ar); dC(50 MHz, CDCl3) −0.32 (2 C), 13.92 (2 C), 40.12,
61.24 (2 C), 63.36, 117.99, 127.46 (2 C), 128.60, 131.04, 133.83,
134.05 (2 C), 139.92, 147.46 and 170.52 (2 C); m/z (EI) 345
(M+ − Me, 100%), 319 (5.5), 287 (10), 285 (11), 283 (82), 271
(29), 244 (8), 227 (13), 209 (28), 199 (21), 165 (14), 135 (60), 121
(22) and 105 (27).
1112 (SiPh); dH(200 MHz, CDCl3) 0.41 (6 H, s, 2 × SiMe), 1.20
(6 H, t, J = 7.1 Hz, 2 × MeCH2OCO), 4.10 (4 H, q, J = 7.1 Hz,
2 × MeCH2OCO), 4.14 (1 H, br s, HC(CO2Et)2), 5.76 (1 H, d,
=
=
J = 1.4 Hz, SiC CH), 6.03 (1 H, t, br, J = 1.1 Hz, SiC CH) and
7.32–7.55 (5 H, m, Ar); dC(50 MHz, CDCl3) −2.81 (2 C), 13.79
(2 C), 56.82, 61.24 (2 C), 127.59 (2 C), 129.06, 132.21, 133.97 (2
C), 136.99, 141.83 and 168.10 (2 C); m/z (EI) 305 (M+ − Me,
99%), 275 (9), 247 (16), 243 (100), 231 (41), 215 (21), 187 (58),
169 (40), 161 (42), 159 (22), 137 (47), 135 (88), 125 (36) and 105
(78).
Diethyl benzyl(1-dimethyl[phenyl]silylvinyl)malonate
5e.
Procedure as described for the preparation of 5b except 2.5
equiv of benzyl bromide were used; yield 64% (found: C, 70.45;
H, 7.68. C24H30O4Si requires C, 70.20; H, 7.36%); Rf 0.37
Diethyl (1-dimethyl[phenyl]silylvinyl)methylmalonate 5b.
A
(hexane–EtOAc, 98 : 2); mmax(neat)/cm−1 1732 (C O), 1248
=
solution of sodium dimsylate (7.5 mmol) in DMSO (7.5 cm3)
was prepared. The solution was diluted with THF (9 cm3) and
cooled on an ice–salt bath (−8 ◦C). Solid trimethylsulfonium
iodide (735 mg, 3.6 mmol) was introduced into the flask and
the reaction mixture was stirred under the same conditions for
15 min. A solution of the 2-silyl alkylidene malonate 2a (0.92 gm,
3 mmol) in dry THF (9 cm3) was rapidly added to the reaction
mixture. It was slowly brought to room temperature (about 2.5 h)
and stirred for 45 min. The reaction mixture was cooled on an
ice–water bath and MeI (0.94 cm3, 15 mmol) was added. After
14 h at room temperature, the reaction mixture was diluted
with water and extracted with ether. The organic extract was
washed with brine, dried (MgSO4) and evaporated. The residue
was purified by column chromatography on silica using hexane–
EtOAc (95 : 5) as eluent to give the vinyl silane 5b (800 mg,
80%) (found: C, 64.21; H, 8.10. C18H26O4Si requires C, 64.63; H,
7.84%); Rf 0.46 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1 1731
(SiMe) and 1111 (SiPh); dH(200 MHz, CDCl3) 0.23 (6 H, s, 2 ×
SiMe), 1.11 (6 H, t, J = 7.1 Hz, 2 × MeCH2OCO), 3.43 (2 H, s,
PhCH2), 4.03 (4 H, q, J = 7.1 Hz, 2 × MeCH2OCO), 5.73 (1
=
=
H, s, SiC CH), 6.06 (1 H, s, SiC CH) and 7.10–7.50 (10 H, m,
Ar); dC(50 MHz, CDCl3) −0.60 (2 C), 13.74 (2 C), 42.55, 61.24
(2 C), 64.76, 126.76, 127.34 (2 C), 127.87 (2 C), 128.35, 130.73
(2 C), 132.02, 134.03 (2 C), 136.56, 140.53, 148.48 and 170.49
(2 C); m/z (EI) 395 (M+ − Me, 0.5%), 333 (24), 215 (31), 199
(20), 158 (15), 137 (29), 135 (58), 129 (20), 128 (16), 105 (35), 91
(100), 77 (13) and 75 (22).
Diethyl (1-dimethyl[phenyl]silylvinyl)(3-methoxybenzyl)malo-
nate 5f. Procedure as described for the preparation of 5b except
2.5 equiv of 3-methoxy benzyl bromide were used; yield 68%
(found: C, 67.85; H, 7.54. C25H32O5Si requires C, 68.15; H,
7.32%; Found: M+ + Na, 463.1933, C25H32O5SiNa requires
(M+ + Na), 463.1917) Rf = 0.33 (hexane–EtOAc, 5 : 95);
(C O), 1259 (SiMe) and 1110 (SiPh); dH(200 MHz, CDCl3)
mmax(neat)/cm−1 1729 (C O), 1260 (SiMe) and 1111 (SiPh);
=
=
3 3 7 4
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8

View Article Online
=
dH(200 MHz, CDCl3) 0.24 (6 H, s, 2 × SiMe), 1.13 (6 H, t,
J = 7.2 Hz, 2 × MeCH2OCO), 3.41 (2 H, s, ArCH2), 3.76 (3
H, s, OMe), 4.05 (4 H, q, J = 7.2 Hz, 2 × MeCH2OCO), 5.73
MeC(CO2Et)2), 1.95–2.15 (2 H, m, MeCH2CH CH), 4.18 (4 H,
q, J = 7 Hz, 2 × MeCH2OCO), 5.60 (1 H, td, J = 6 and 16 Hz,
=
=
MeCH2CH CH), 5.88 (1 H, d, J = 16 Hz, MeCH2CH CH);
dC(50 MHz, CDCl3) 13.29, 13.95 (2 C), 20.32, 25.60, 55.32, 61.35
(2 C), 126.86, 133.60, 171.51 (2 C).
=
=
(1 H, s, SiC CH), 6.06 (1 H, s, SiC CH), 6.70–6.78 (3 H, m,
Ar), 7.14 (1 H, t, J = 8 Hz, Ar), 7.27–7.36 (3 H, m, Ar), 7.45–
7.50 (2 H, m, Ar); dC(50 MHz, CDCl3) −0.6 (2 C), 13.74 (2 C),
42.53, 55.06, 61.24 (2 C), 64.67, 112.27, 116.37, 123.11, 127.31 (2
C), 128.31, 128.76, 131.99, 133.99 (2 C), 137.98, 140.52, 148.42,
159.13, 170.41 (2 C); m/z (ESI) 463 (M+ + Na, 61%), 363 (100),
317 (18), 245 (9).
Ethyl 2-diethylphosphonato-2-methyl-3-(4-methoxyphenyl)but-
3-enoate 5k. Procedure as described for the preparation of 5b;
yield 50%, Rf 0.5 (hexane–EtOAc, 70 : 30); mmax(neat)/cm−1 1731
=
=
=
(C O), 1608 (C C), 1247 (P O) and 1028 (P–O); dH(200 MHz,
CDCl3) 1.02 (3 H, t, J = 7.1 Hz, MeCH2OCO), 1.26 (3 H, t,
J = 6.9 Hz, MeCH2OP), 1.29 (3 H, t, J = 6.8 Hz, MeCH2OP),
1.64 (3 H, d, J = 15.7 Hz, MeC(CO2Et)(EtO)2P(O)), 3.74 (3
H, s, MeOAr), 3.85–4.05 (2 H, m, MeCH2OP), 4.05–4.26 (4 H,
m, MeCH2OP and MeCH2OCO), 5.28 (1 H, d, J = 4.4 Hz,
Diethyl methyl(1-phenylvinyl)malonate 5g. Procedure as de-
scribed for the preparation of 5b; yield 73% (found: C, 69.30; H,
7.52. C16H20O4 requires C, 69.55; H, 7.30%); Rf 0.40 (hexane–
EtOAc, 95 : 5); mmax(neat)/cm−1 1728 (C O); dH(200 MHz,
=
=
=
ArC CH), 5.61 (1 H, d, J = 4.2 Hz, ArC CH), 6.76 (2 H, d,
J = 8.4 Hz, Ar) and 7.22 (2 H, d, J = 8.4 Hz, Ar); dC(50 MHz,
CDCl3) 13.48, 16.25 (2 C, d, J = 5.5 Hz), 21.63 (d, J = 5 Hz),
54.39 (d, J = 140 Hz), 55.02, 61.23, 62.89 (2 C, d, J = 4.3 Hz),
112.80 (2 C), 119.09 (d, J = 8.1 Hz), 129.34 (2 C), 133.82 (d, J =
4.9 Hz), 145.79 (d, J = 7 Hz), 158.63 and 170.98; m/z (EI) 370
(M+, 0.1%), 325 (0.5), 297 (16), 233 100), 205 (46), 159 (30), 145
(11) and 121 (20).
CDCl3) 1.20 (6 H, t, J = 7.1 Hz, 2 × MeCH2OCO), 1.60 (3 H, s,
MeC(CO2Et)2), 4.18 (4 H, q, J = 7.1 Hz, 2 × MeCH2OCO),
=
5.34 (2 H, s, ArC CH2) and 7.36 (5 H, br s, Ar); dC(50 MHz,
CDCl3) 13.82 (2 C), 22.26, 60.03, 61.59 (2 C), 118.03, 127.34,
127.82 (2 C), 128.24 (2 C), 140.76, 147.78 and 171.33 (2 C); m/z
(EI) 276 (M+, 0.5%), 231 (0.5), 203 (100), 185 (11), 175 (89), 147
(16), 129 (64), 115 (33) and 91 (27).
Diethyl (1-[4-methoxyphenyl]vinyl)methylmalonate 5h. Pro-
cedure as described for the preparation of 5b; yield 57% (found:
C, 66.22; H, 7.41. C17H22O5 requires C, 66.65; H, 7.24%); Rf
Ethyl 2-cyano-3-dimethyl(phenyl)silyl-2-methylbut-3-enoate
5l. Procedure as described for the preparation of 5b; yield
28% (found: C, 66.95; H, 7.55; N, 4.45. C16H21NO2Si requires
C, 66.86; H, 7.36; N, 4.87%). Rf 0.42 (hexane–EtOAc, 98 : 2);
0.24 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1 1731 (C O) and
=
=
1609 (C C); dH(200 MHz, CDCl3) 1.20 (6 H, t, J = 7.1 Hz,
mmax(neat)/cm−1 2241 (CN), 1745 (C O), 1251 (SiMe) and 1113
=
2 × MeCH2OCO), 1.58 (3 H, s, MeC(CO2Et)2), 3.77 (3 H, s,
MeOAr), 4.17 (4 H, q, J = 7.1 Hz, 2 × MeCH2OCO), 5.26 (1
(SiAr); dH(200 MHz, CDCl3) 0.49 (3 H, s, SiMe), 0.52 (3 H, s,
SiMe), 1.19 (3 H, t, J = 7.1 Hz, MeCH2OCO), 1.65 (3 H, s,
MeC(CO2Et)(CN)), 3.77–4.10 (2 H, m, MeCH2OCO), 5.78 (1
H, s, SiC CH), 6.24 (1 H, s, SiC CH) and 7.33–7.55 (5 H,
m, Ar); dC(50 MHz, CDCl3) −1.46, −1.37, 13.67, 24.13, 49.36,
62.77, 119.52, 127.79 (2 C), 129.43, 131.34, 134.04 (2 C), 136.72,
145.20 and 168.01; m/z (EI) 272 (M+ − Me, 29%), 244 (13), 210
(47), 200 (67), 173 (84), 135 (100) and 111 (51).
=
=
H, s, ArC CH), 5.29 (1 H, s, ArC CH), 6.79 (2 H, d, J =
8.6 Hz, Ar) and 7.18 (2 H, d, J = 8.6 Hz, Ar); dC(50 MHz,
CDCl3) 13.79 (2 C), 22.15, 55.09, 60.09, 61.50 (2 C), 113.10 (2
C), 117.24, 129.35 (2 C), 133.03, 147.26, 158.84 and 171.35 (2
C); m/z (EI) 307 (M+ + 1, 2.5%), 306 (2.5), 261 (2), 233 (100),
205 (80), 187 (11), 177 (25), 159 (46), 145 (17), 115 (21) and 91
(20).
=
=
Ethyl 2-cyano-2-methyl-3-(4-methoxyphenyl)but-3-enoate 5m
and ethyl (Z)-2-cyano-2-methyl-3-(4-methoxyphenyl)pent-3-
enoate 8. Procedure as described for the preparation of
5b; yield 60%; ratio of 5m/8 = 65 : 35; the individual
components could not be separated from the mixture. Data for
8: dH(200 MHz, CDCl3) (recognizable peaks) 1.25 (3 H, t, J =
Diethyl (1-[4-bromophenyl]vinyl)methylmalonate 5i. Proce-
dure as described for the preparation of 5b; yield 69%
(found: C, 53.88; H, 5.40. C16H19BrO4 requires C, 54.10; H,
5.39%); Rf 0.40 (hexane–EtOAc, 95 : 5); mmax(neat)/cm−1 1732
=
(C O);dH(200 MHz, CDCl3) 1.21 (6 H, t, J = 7.1 Hz, 2 ×
MeCH2OCO), 1.59 (3 H, s, MeC(CO2Et)2), 4.17 (4 H, q, J =
=
6.7 Hz, MeCH2OCO), 1.50 (3 H, d, J = 6.7 Hz, MeCH C),
=
7.1 Hz, 2 × MeCH2OCO), 5.33 (1 H, s, ArC CH), 5.36 (1 H, s,
1.66 (3 H, s, MeC(CO2Et)(CN)), 3.81 (3 H, s, MeOAr), 4.18 (2
H, q, J = 6.7 Hz, MeCH2OCO) and 6.18 (1 H, q, J = 6.7 Hz,
=
ArC CH), 7.16 (2 H, d, J = 8.4 Hz, Ar) and 7.40 (2 H, d, J =
8.4 Hz, Ar); dC(50 MHz, CDCl3) 13.84 (2 C), 22.21, 59.85, 61.71
(2 C), 118.65, 121.52, 130.05 (2 C), 130.94 (2 C), 139.77, 146.79
and 171.11 (2 C); m/z (EI) 356 (C16H19O481Br, M+, 0.2%), 354
(C16H19O479Br, M+, 0.25), 311 (0.5), 309 (0.6), 283 (76), 281 (78),
255 (67), 253 (69), 227 (8), 225 (8), 207 (11), 207 (12), 146 (15),
130 (42), 129 (44), 128 (100), 127 (41), 115 (30) and 102 (26).
=
ArC CH).
Ethyl 2-cyano-2-methyl-3-(4-methoxyphenyl)but-3-enoate 5m
A solution of sodium dimsylate (2.5 mmol, 2.5 equiv) in
DMSO (2.5 cm3) was prepared. The solution was diluted with
THF (3 cm3) and cooled on an ice–salt bath (−8 ◦C). Solid
trimethylsulfonium iodide (245 mg, 1.2 mmol, 1.2 equiv) was
introduced into the flask and the reaction mixture was stirred
under the same conditions for 15 min. A solution of the arylidene
cyanoacetate 2i (0.231 gm, 1 mmol, 1 equiv) in dry THF (3 cm3)
was rapidly added to the reaction mixture. It was slowly brought
to room temperature (about 2.5 h) and stirred for 45 min. The
reaction mixture was cooled on an ice–water bath and a warm
solution of MgBr2 (920 mg, 5 mmol) in THF (10 cm3) was
added into the reaction mixture. After 15 min, MeI (0.5 cm3,
8 mmol, 8 equiv) was added to the above slurry and allowed
to attain room temperature. After 14 h at room temperature,
the reaction mixture was diluted with water and extracted
with ether. The organic extract was washed with brine, dried
(MgSO4) and evaporated. The residue was purified by column
chromatography on silica using hexane–EtOAc (95 : 5) as eluent
to give the styrene 5m (44 mg, 17%) (found: C, 69.22; H, 6.87;
N, 5.12. C15H17O3N requires C, 69.48; H, 6.61; N, 5.40%); Rf
0.37 (hexane–EtOAc, 98 : 2); mmax(neat)/cm−1 2240 (CN), 1746
Diethyl methyl(1-[4-nitrophenyl]vinyl)malonate 5j. Proce-
dure as described for the preparation of 5b; yield 20% (found: C,
60.06; H, 6.00; N, 4.11. C16H19NO6 requires C, 59.81; H, 5.96; N,
4.36%); Rf 0.36 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1 1728
=
=
(C O), 1598 (C C) and 1521 (NO2); dH(200 MHz, CDCl3)
1.20 (6 H, t, J = 7.1 Hz, 2 × MeCH2OCO), 1.65 (3 H, s,
MeC(CO2Et)2), 4.17 (4 H, q, J = 7.1 Hz, 2 × MeCH2OCO),
=
=
5.43 (1 H, s, ArC CH), 5.51 (1 H, s, ArC CH), 7.48 (2 H, d,
J = 8.6 Hz, Ar) and 8.15 (2 H, d, J = 8.6 Hz, Ar); dC(50 MHz,
CDCl3) 13.74 (2 C), 22.22, 59.57, 61.80 (2 C), 120.19, 122.97 (2
C), 129.20 (2 C), 146.22, 147.01, 147.75 and 170.67 (2 C); m/z
(EI) 276 (M+ − OEt, 0.5%), 248 (80), 220 (100), 174 (19), 129
(26), 128 (41) and 115 (18).
Diethyl (E)-(1-butenyl)methylmalonate 724. Procedure as de-
scribed for the preparation of 5b; yield 37%, Rf 0.4 (hexane–
EtOAc, 95 : 5); mmax(neat)/cm−1 1733 (C O), 970 (trans-C C);
dH(200 MHz, CDCl3) 0.98 (3 H, t, J = 7.4 Hz, MeCH2CH CH),
=
=
=
1.23 (6 H, t, J = 7 Hz, 2 × MeCH2OCO), 1.51 (3 H, s,
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8
3 3 7 5

View Article Online
=
=
(C O) and 1608 (C C); dH(200 MHz, CDCl3) 1.22 (3 H, t, J =
7.2 Hz, MeCH2OCO), 1.79 (3 H, s, MeC(CO2Et)(CN)), 3.81 (3
H, s, MeOAr), 4.21 (2 H, q, J = 7.2 Hz, MeCH2OCO), 5.42
131.61, 158.73, 167.54, 168.21; m/z (ESI) 363 (M+ + Na, 70%),
181 (100), 159 (15) and 79 (8).
Diethyl (1-[4-bromophenyl]vinyl)malonate 5p. Procedure as
described for the preparation of 5a. After the usual workup, the
residue was purified by column chromatography on silica using
hexane–EtOAc (95 : 5) as eluent to give the styrene 5p (66%)
and diethyl (1-[4-bromophenyl]-2-thiomethyl)ethylmalonate11d
(7%).
=
=
(1 H, s, ArC CH), 5.63 (1 H, s, ArC CH), 6.85 (2 H, d, J =
8.7 Hz, Ar) and 7.22 (2 H, d, J = 8.7 Hz, Ar); dC(50 MHz,
CDCl3) 13.76, 23.19, 48.87, 55.24, 63.08, 113.62 (2 C), 118.10,
119.41, 129.20 (2 C), 130.39, 143.92, 159.60 and 167.85; m/z
(EI) 260 (M+ + 1, 3.8%), 259 (20), 244 (3), 233 (4), 186 (17), 172
(10), 144 (13), 135 (28), 133 (100), 121 (28), 108 (24), 91 (10), 89
(12) and 77 (22).
Data for diethyl (1-[4-bromophenyl]vinyl)malonate 5p.
(Found: M+ + Na, 363.0210. C15H17O4BrNa requires M+ + Na,
363.0208); mmax(neat)/cm−1 1734 (C O); dH(200 MHz, CDCl3)
Diethyl (1-[phenyl]vinyl)malonate 5n. Procedure as described
for the preparation of 5a. After the usual workup, the residue
was purified by column chromatography on silica using hexane–
EtOAc (95 : 5) as eluent to give the styrene 5n (65%) and diethyl
(1-phenyl-2-thiomethyl)ethylmalonate 11b (15%).
=
1.23 (6 H, t, J = 7.2 Hz, 2 × MeCH2OCO), 4.20 (4 H, q, J =
7.2 Hz, 2 × MeCH2OCO), 4.55 (1 H, s, HC(CO2Et)2), 5.43
=
=
(1 H, s, ArC CH), 5.61 (1 H, s, ArC CH), 7.27 (2 H, d, J =
8.5 Hz, Ar) and 7.45 (2 H, d, J = 8.5 Hz, Ar); dC(50 MHz,
CDCl3) 13.86 (2 C), 57.00, 61.79 (2 C), 118.38, 121.95, 127.93
(2 C), 131.43 (2 C), 138.96, 139.69 and 167.59 (2 C); m/z (ESI)
365 (81Br M+ + Na, 60%), 363 (79Br M+ + Na, 54) and 99 (100).
Data for diethyl (1-[4-bromophenyl]-2-thiomethyl)ethyl-
malonate 11d. (Found: M+ + Na, 411.0258. C16H21O4BrSNa
requires M+ + Na, 411.0242); Rf 0.30 (hexane–EtOAc, 95 : 5);
Data for diethyl (1-[phenyl]vinyl)malonate 5n. (Found: M+ +
Na, 285.1101. C15H18O4Na requires M+ + Na, 285.1103); Rf
0.55 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1 1736 (C O) and
=
1631 (Ar); dH(200 MHz, CDCl3) 1.24 (6 H, t, J = 7.2 Hz, 2 ×
MeCH2OCO), 4.21 (4 H, q, J = 7.2 Hz, 2 × MeCH2OCO), 4.62
=
(1 H, s, HC(CO2Et)2), 5.42 (1 H, s, PhC CH), 5.64 (1 H, s,
mmax(neat)/cm−1 1730 (C O); dH(200 MHz, CDCl3) 1.00 (3 H, t,
=
PhC CH) and 7.28–7.44 (m, 5 H, Ph); dC(50 MHz, CDCl3)
=
13.66 (2 C), 56.88, 61.47 (2 C), 117.35, 125.96 (2 C), 127.69,
128.17 (2 C), 139.89, 140.47 and 167.61 (2 C); m/z (ESI) 285
(M+ + Na, 100%), 115 (74) and 99 (28).
J = 7 Hz, MeCH2OCO), 1.28 (3 H, t, J = 7 Hz, MeCH2OCO),
1.99 (3 H, s, SMe), 2.74 (1 H, dd, J = 9 and 13 Hz, CHAHBSMe),
2.91 (1 H, dd, J = 4.4 and 13 Hz, CHAHBSMe), 3.62 (1 H, dt, J =
4.4 and 9 Hz, CHAr), 3.74 (1 H, d, J = 10.2 Hz, HC(CO2Et)2),
3.93 (2 H, q, J = 7 Hz, MeCH2OCO), 4.23 (2 H, q, J = 7 Hz,
MeCH2OCO), 7.13 (2 H, d, J = 8.4 Hz, Ar) and 7.43 (2 H, d,
J = 8.4 Hz, Ar); dC(50 MHz, CDCl3) 13.67, 13.98, 15.92, 38.45,
44.36, 56.96, 61.40, 61.75, 121.22, 130.10 (2 C), 131.41 (2 C),
138.73, 167.21, 167.82; m/z (ESI) 413 (81Br M+ + Na, 36%), 411
(79Br M+ + Na, 42), 231 (24), 239 (36), 156 (21), 124 (27), 99
(100) and 77 (36).
Data for diethyl (1-phenyl-2-thiomethyl)ethylmalonate 11b.
(Found: M+ + Na, 333.1126. C16H22O4SNa requires M+ + Na,
333.1137); Rf 0.50 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1
=
1732 (C O); dH(200 MHz, CDCl3) 0.93 (3 H, t, J = 7.2 Hz,
MeCH2OCO), 1.26 (3 H, t, J = 7.2 Hz, MeCH2OCO), 1.96 (3
H, s, SMe), 2.78 (1 H, dd, J = 8.8 and 13.2 Hz, CHAHBSMe),
2.92 (1 H, dd, J = 4.6 and 13.2 Hz, CHAHBSMe), 3.63 (1 H,
dt, J = 4.6 and 10.2 Hz, CHPh), 3.77 (1 H, d, J = 10.4 Hz,
HC(CO2Et)2), 3.88 (2 H, q, J = 7.2 Hz, MeCH2OCO), 4.22 (2
H, q, J = 7.2 Hz, MeCH2OCO) and 7.20–7.32 (m, 5 H, Ph);
dC(50 MHz, CDCl3) 13.57, 13.94, 15.85, 38.68, 44.96, 57.25,
61.19, 61.59, 127.26, 128.25 (2 C), 129.31 (2 C), 139.61, 167.37,
168.05; m/z (ESI) 333 (M+ + Na, 100%), 161 (23), 124 (79), and
77 (68).
Diethyl (1-[4-nitrophenyl]vinyl)malonate 5q. Procedure as
described for the preparation of 5a. After the usual workup, the
residue was purified by column chromatography on silica using
hexane–EtOAc (95 : 5) as eluent to give the styrene 5q (46%) and
diethyl (1-[4-nitrophenyl]-2-thiomethyl)ethylmalonate 11e (8%).
Data for diethyl (1-[4-nitrophenyl]vinyl)malonate 5q.
Diethyl (1-[4-methoxyphenyl]vinyl)malonate 5o. Procedure
as described for the preparation of 5a. After the usual
workup, the residue was purified by column chromatography
on silica using hexane–EtOAc (95 : 5) as eluent to give
the vinyl silane 50 (61%) and diethyl (1-[4-methoxyphenyl]-2-
thiomethyl)ethylmalonate 11c (20%).
Data for diethyl (1-[4-methoxyphenyl]vinyl)malonate 5o.
(Found: M+ + Na, 315.1219. C16H20O5Na requires M+ + Na,
315.1208); Rf 0.45 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1
(Found: M+ + Na, 330. 0953. C15H17O6NNa requires M+
+
Na, 330.0954); Rf 0.46 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1
=
1740 (C O); dH(200 MHz, CDCl3) 1.24 (6 H, t, J = 7.2 Hz, 2 ×
MeCH2OCO), 4.22 (4 H, q, J = 7.2 Hz, 2 × MeCH2OCO), 4.59
=
(1 H, s, HC(CO2Et)2), 5.61 (1 H, s, ArC CH), 5.75 (1 H, s,
ArC CH), 7.57 (2 H, d, J = 8.8 Hz, Ar) and 8.19 (2 H, d, J =
=
8.8 Hz, Ar); dC(50 MHz, CDCl3) 13.71 (2 C), 56.73, 61.85 (2 C),
121.16, 123.46 (2 C), 127.16 (2 C), 139.07, 146.35, 147.09, 167.17
(2 C); m/z (ESI) 330 (M+ + Na, 100%), 308 (41), 262 (33), 216
(75), 159 (12), 156 (41) and 79 (12).
=
1734 (C O) and 1608 (Ar); dH(200 MHz, CDCl3) 1.24 (6 H,
t, J = 7.2 Hz, 2 × MeCH2OCO), 3.80 (3 H, s, –OCH3), 4.21 (4
Data for diethyl (1-[4-nitrophenyl]-2-thiomethyl)ethylmalo-
nate 11e. (Found: M+ + Na, 378.0982. C16H21O6NSNa re-
quires M+ + Na, 378.0987); Rf 0.35 (hexane–EtOAc, 90 :
H, q, J = 7.2 Hz, 2 × MeCH2OCO), 4.59 (1 H, s, HC(CO2Et)2),
=
=
5.31 (1 H, s, ArC CH), 5.56 (1 H, s, ArC CH), 6.86 (2 H, d,
J = 8.8 Hz, Ar) and 7.34 (2 H, d, J = 8.8 Hz, Ar); dC(50 MHz,
CDCl3) 13.77 (2 C), 55.02, 57.08, 61.52 (2 C), 113.56 (2 C),
115.85, 127.22 (2 C), 132.32, 139.95, 159.26 and 167.79 (2 C);
m/z (ESI) 315 (M+ + Na, 8%) and 99 (100).
10); mmax(neat)/cm−1 1737 (C O); dH(200 MHz, CDCl3) 1.01
=
(3 H, t, J = 7 Hz, MeCH2OCO), 1.29 (3 H, t, J = 7.2 Hz,
MeCH2OCO), 2.02 (3 H, s, SMe), 2.79 (1 H, dd, J = 7.6 and
13 Hz, CHAHBSMe), 2.95 (1 H, d, J = 13 Hz, CHAHBSMe),
3.73–3.83 (2 H, m, CHAr and HC(CO2Et)2), 3.95 (2 H, q, J =
7.2 Hz, MeCH2OCO), 4.25 (2 H, q, J = 7 Hz, MeCH2OCO),
7.44 (2 H, d, J = 8.6 Hz, Ar) and 8.18 (2 H, d, J = 8.6 Hz, Ar);
dC(50 MHz, CDCl3) 13.73, 13.99, 15.96, 38.23, 44.60, 56.61,
61.64, 62.00, 123.51 (2 C), 129.44 (2 C), 147.15, 147.54, 166.97,
167.53; m/z (ESI) 378 (M+ + Na, 1%), 164 (23) and 104 (100).).
Data for diethyl (1-[4-methoxyphenyl]-2-thiomethyl)ethyl-
malonate 11c. (Found: M+ + Na, 363.1246. C17H24O5SNa
requires M+ + Na, 363.1242); Rf 0.38 (hexane–EtOAc, 90 :
10); mmax(neat)/cm−1 1743 (C O); dH(200 MHz, CDCl3) 0.99
=
(3 H, t, J = 7 Hz, MeCH2OCO), 1.28 (3 H, t, J = 7.2 Hz,
MeCH2OCO), 1.98 (3 H, s, SMe), 2.75(1 H, dd, J = 4 and
13.2 Hz, CHAHBSMe), 2.90 (1 H, dd, J = 4.4 and 13.2 Hz,
CHAHBSMe), 3.62 (1 H, dt, J = 6.6 and 10 Hz, CHAr), 3.74
(1 H, d, J = 10 Hz, HC(CO2Et)2), 3.77 (3 H, s, ArOMe), 3.92
(2 H, q, J = 7 Hz, MeCH2OCO), 4.22 (2 H, q, J = 7.2 Hz,
MeCH2OCO), 6.83 (2 H, d, J = 8.6 Hz, Ar) and 7.16 (2 H, d,
J = 8.6 Hz, Ar); dC(50 MHz, CDCl3) 13.76, 14.05, 15.96, 38.92,
44.25, 55.15, 57.54, 61.28, 61.66, 113.71 (2 C), 129.39 (2 C),
Diethyl (1-[3-methoxyphenyl]vinyl)malonate 5r. Procedure
as described for the preparation of 5a. After the usual workup,
the residue was purified by column chromatography on silica
using hexane–EtOAc (95 : 5) as eluent to give the styrene 5r (46%)
and diethyl (1-[3-methoxyphenyl]-2-thiomethyl)ethylmalonate
11j (8%).
3 3 7 6
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8

View Article Online
Data for diethyl (1-[3-methoxyphenyl]vinyl)malonate 5r.
(Found: M+ + Na, 315.1206. C16H20O5Na requires M+ + Na,
315.1208); Rf 0.46 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1
17.98, 55.72, 61.54 (2 C), 122.51, 131.67, 168.47 (2 C); m/z (ESI)
223 (M+ + Na, 100%), 166 (15) and 164 (50).
Da◦ta for diethyl 2-(1-thiomethyl)butylmalonate 11l. Bp 125–
130 C (bath)/0.3 mmHg; (found: M+ + Na, 285.1145.
C12H22O4SNa requires M+ + Na, 285.1137); Rf 0.35 (hexane–
=
1734 (C O); dH(200 MHz, CDCl3) 1.24 (6 H, t, J = 7.2 Hz,
2 × MeCH2OCO), 3.81 (3 H, s, OMe), 4.21 (4 H, q, J = 7.2 Hz,
2 × MeCH2OCO), 4.60 (1 H, s, HC(CO2Et)2), 5.42 (1 H, s,
EtOAc, 95 : 5); mmax(neat)/cm−1 1733 (C O); dH(200 MHz,
=
=
=
ArC CH), 5.64 (1 H, s, ArC CH), 6.84 (1 H, dd, J = 2 and
7.8 Hz, Ar), 6.96 (1 H, d, J = 1.2 Hz, Ar), 6.98 (1 H, d, J =
7.7 Hz, Ar), and 7.24 (1 H, t, J = 7.8 Hz, Ar); dC(50 MHz,
CDCl3) 13.93 (2 C), 55.19, 57.12, 61.75 (2 C), 112.05, 113.39,
117.78, 118.64, 129.38, 140.53, 141.68, 159.55, 167.85 (2 C); m/z
(ESI) 315 (M+ + Na, 31%), 201 (100), 173 (70), and 145 (84).
Data for diethyl (1-[3-methoxyphenyl]-2-thiomethyl)ethyl-
malonate 11j. (Found: M+ + Na, 363.1237. C17H24O5SNa
requires M+ + Na, 363.1242); Rf 0.35 (hexane–EtOAc, 90 :
CDCl3) 0.92 (3 H, t, J = 7.4 Hz, MeCH2), 1.26 (6 H, t, J =
7.2 Hz, 2 × MeCH2OCO), 1.46–1.62 (2 H, m, MeCH2), 2.08 (3
H, s, SMe), 2.18–2.34 (1 H, m, MeCH2CH), 2.50–2.70 (2 H, m,
CH2SMe), 3.65 (1 H, d, J = 6.6 Hz, HC(CO2Et)2), 4.19 (4 H,
q, J = 7.2 Hz, 2 × MeCH2OCO); dC(50 MHz, CDCl3) 11.14,
14.03 (2 C), 15.89, 23.33, 35.83, 39.43, 53.77, 61.21 (2 C), 168.77
(2 C); m/z (ESI) 285 (M+ + Na, 31%), 200 (12), 168 (24), 166
(35), 164 (100), 159 (32), 104 (15), 99 (38) and 73 (84).
10); mmax(neat)/cm−1 1738 (C O); dH(200 MHz, CDCl3) 0.98
=
Ethyl 2-cyano-3-(4-methoxyphenyl)-but-3-enoate 5t. Proce-
dure as described for the preparation of 5a. After the usual
workup, the residue was purified by column chromatography
on silica using hexane–EtOAc (95 : 5) as eluent to give ethyl 2-
cyano-3-(4-methoxyphenyl)-but-3-enoate 5t (37%), ethyl (E)-2-
cyano-3-(4-methoxyphenyl)-but-2-enoate E-10i (14%) and ethyl
(Z)-2-cyano-3-(4-methoxyphenyl)-but-2-enoate Z-10i (4%).
Data for ethyl 2-cyano-3-(4-methoxyphenyl)-but-3-enoate 5t.
(Found: M+ + H, 246.1126. C14H16O3N requires M+ + H,
246.1130); Rf 0.45 (hexane–EtOAc, 90 : 10); dH(200 MHz,
CDCl3) 1.23 (3 H, t, J = 7 Hz, MeCH2OCO), 3.79 (3
H, s, OMe), 4.20 (2 H, q, J = 7 Hz, MeCH2OCO), 4.59 (1
(3 H, t, J = 7.2 Hz, MeCH2OCO), 1.27 (3 H, t, J = 7.2 Hz,
MeCH2OCO), 1.98 (3 H, s, SMe), 2.72–2.98 (2 H, m, CH2SMe),
3.55–3.67 (1 H, m, CHAr), 3.75 (1 H, d, J = 8 Hz, HC(CO2Et)2),
3.78 (3 H, s, ArOMe), 3.92 (2 H, q, J = 7.2 Hz, MeCH2OCO),
4.22 (2 H, q, J = 7 Hz, MeCH2OCO), 6.75–6.85 (3 H, m, Ar) and
7.18 (1 H, d, J = 8.8 Hz, Ar); dC(50 MHz, CDCl3) 13.62, 13.95,
15.91, 38.61, 44.95, 55.04, 57.21, 61.22, 61.60, 112.50, 114.24,
120.56, 129.22, 141.26, 159.39, 167.36, 168.04; m/z (ESI) 363
(M+ + Na, 79%), 319 (13), 249 (90), 181 (100), 179 (20) and 134
(13).
Diethyl (1-[3-chlorophenyl]vinyl)malonate 5s. Procedure as
described for the preparation of 5a. After the usual workup, the
residue was purified by column chromatography on silica using
hexane–EtOAc (95 : 5) as eluent to give the styrene 5s (46%)
and diethyl (1-[3-chlorophenyl]-2-thiomethyl)ethylmalonate 11k
(8%).
=
H, s, HC(CO2Et)CN), 5.31 (1 H, s, ArC CH), 5.55 (1 H, s,
ArC CH), 6.85 (2 H, d, J = 8.8 Hz, Ar), 7.34 (2 H, d, J = 8.8 Hz,
=
Ar); dC(50 MHz, CDCl3) 13.92, 55.21, 57.23, 61.69, 113.70 (2
C), 116.07, 127.37 (2 C), 132.50, 140.04, 159.36, 167.96 (2 C);
m/z (ESI) 246 (M+ + H, 3%), 201 (68), 200 (100) and 158 (13).
Data for ethyl (E)-2-cyano-3-(4-methoxyphenyl)-but-2-
enoate E-10i. (Found: M+ + Na, 268.0940. C14H15O3NNa
requires M+ + Na, 268.0950); Rf 0.35 (hexane–EtOAc, 90 :
Data for diethyl (1-[3-chlorophenyl]vinyl)malonate 5s.
(Found: M+ + Na, 319.0717. C15H17O4ClNa requires M+ + Na,
319.0713); mmax(neat)/cm−1 1733 (C O); dH(200 MHz, CDCl3)
=
10); mmax(neat)/cm−1 2222 (CN), 1726 (C O) and 1605 (C C);
dH(200 MHz, CDCl3) 1.37 (3 H, t, J = 7.2 Hz, MeCH2OCO),
=
=
1.24 (6 H, t, J = 7.2 Hz, 2 × MeCH2OCO), 4.22 (4 H, q, J =
7.2 Hz, 2 × MeCH2OCO), 4.55 (1 H, s, HC(CO2Et)2), 5.46 (1
=
2.67 (3 H, s, C CMe), 3.84 (3 H, s, OMe), 4.32 (2 H, q, J =
=
=
H, s, ArC CH), 5.63 (1 H, s, ArC CH), 7.27 (3 H, s, broad, Ar),
7.40 (1 H, s, Ar); dC(50 MHz, CDCl3) 13.85 (2 C), 56.98, 61.80
(2 C), 118.93, 124.45, 126.54, 127.89, 129.58, 134.25, 139.57,
141.97, 167.51 (2 C); m/z (ESI) 319 (M+ + Na, 11%), 205 (100),
177 (28), and 149 (20).
7.2 Hz, MeCH2OCO), 6.95 (2 H, d, J = 8.8 Hz, Ar), 7.46 (2
H, d, J = 8.8 Hz, Ar); dC(50 MHz, CDCl3) 13.63, 22.60, 54.89,
61.34, 102.88, 113.49 (2 C), 116.47, 128.99 (2 C), 131.65, 161.09,
162.12, 171.46; m/z (ESI) 268 (M+ + Na, 100%), 200 (77) and
99 (58).
Data for diethyl (1-[3-chlorophenyl]-2-thiomethyl)ethyl-
malonate 11k. (Found: M+ + Na, 367.0752. C16H21O4ClSNa
Data for ethyl (Z)-2-cyano-3-(4-methoxyphenyl)-but-2-
requires M+ + Na, 367.0747); mmax(neat)/cm−1 1740 (C O);
enoate Z-10i. Rf 0.30 (hexane–EtOAc, 90 : 10); mmax(neat)/cm−1
=
=
=
dH(200 MHz, CDCl3) 1.00 (3 H, t, J = 7 Hz, MeCH2OCO),
1.28 (3 H, t, J = 7.2 Hz, MeCH2OCO), 2.00 (3 H, s, SMe), 2.77
(1 H, dd, J = 8.8 and 13.2 Hz, CHAHBSMe), 2.92 (1 H, dd,
J = 4.4 and 13.2 Hz, CHAHBSMe), 3.58–3.72 (1 H, m, CHAr),
3.75 (1 H, d, J = 10 Hz, HC(CO2Et)2), 3.91 (2 H, q, J = 7 Hz,
MeCH2OCO), 4.23 (2 H, q, J = 7.2 Hz, MeCH2OCO) and
7.14–7.26 (4 H, m, Ar); dC(50 MHz, CDCl3) 13.57, 13.91, 15.84,
38.35, 44.57, 56.87, 61.32, 61.67, 126.62, 127.41, 128.50, 129.48,
133.99, 141.79, 167.11, 167.72; m/z (ESI) 367 (M+ + Na, 5%),
255 (11), 253 (100) and 185 (55).
2221 (CN), 1735 (C O) and 1605 (C C); dH(200 MHz, CDCl3)
=
1.18 (3 H, t, J = 7.2 Hz, MeCH2OCO), 2.53 (3 H, s, C CMe),
3.82 (3 H, s, OMe), 4.13 (2 H, q, J = 7.2 Hz, MeCH2OCO),
6.89 (2 H, d, J = 8.8 Hz, Ar), 7.17 (2 H, d, J = 8.8 Hz, Ar);
dC(50 MHz, CDCl3) 13.47, 26.05, 54.98, 61.45, 104.19, 113.28 (2
C), 115.78, 128.37 (2 C), 130.30, 160.73, 161.60, 168.74.
2-(2-Methylphenyl)tetrahydrothiophene 2519. Procedure as
described for the preparation of 5a except sulfonium bromide
22 was used instead of Me3SI. Yield: 82%; Rf 0.20 (hexane);
dH(200 MHz, CDCl3) 1.86–2.14 (2 H, m, CH2), 2.20–2.40 (2 H,
m, CH2), 2.38 (3 H, s, ArMe), 2.95–3.05 (1 H, m, SCHAHB),
3.06–3.25 (1 H, m, SCHAHB), 4.74 (1 H, t, J = 7.5 Hz, SCHAr),
7.11–7.24 (3 H, m, Ar), 7.60 (1 H, d, J = 7.3 Hz, Ar).
2-(2-Methylphenyl)tetrahydro-2H-thiopyran 2619. Procedure
as described for the preparation of 5a except sulfonium bromide
23 was used instead of Me3SI. Yield: 71%; Rf 0.30 (hexane);
dH(200 MHz, CDCl3) 1.42–1.85 (2 H, m, CH2), 1.95–2.12 (4 H,
m, 2 × CH2), 2.42 (3 H, s, ArMe), 2.67 (1 H, d, broad, J =
14 Hz, SCHAHB), 2.90 (1 H, dt, J = 2.2 and 12 Hz, SCHAHB),
4.01 (1 H, dd, J = 3.2 and 10 Hz, SCHAr), 7.08–7.24 (3 H, m,
Ar), 7.39 (1 H, d, J = 6.8 Hz, Ar); dC(50 MHz, CDCl3) 19.17,
26.94, 27.41, 31.01, 34.38, 43.36, 126.30, 126.60, 126.88, 130.32,
135.41, 140.74.
Diethyl 2-(1-thiomethyl)butylmalonate 11l. Procedure as de-
scribed for the preparation of 5a. After the usual workup, the
residue was purified by column chromatography on silica using
hexane–EtOAc (95 : 5) as eluent. The residue on short path
distillation gave diethyl (E)-1-propenylmalonate 12 (55%) and
diethyl 2-(1-thiomethyl)butylmalonate 11l (25%).
Data for diethyl (E)-1-propenylmalonate12. Bp 100 ◦C
(bath)/0.3 mmHg; (found: M+ + Na, 223.0941. C10H16O4Na
requires M+ + Na, 223.0946); Rf 0.35 (hexane–EtOAc, 95 : 5);
mmax(neat)/cm−1 1734 (C O) and 972 (trans C C); dH(200 MHz,
CDCl3) 1.29 (6 H, t, J = 7.2 Hz, 2 × MeCH2OCO), 1.74 (3 H,
=
=
=
d, J = 4.4 Hz, MeCH CH), 3.96 (1 H, dd, J = 5.8, 2.4 Hz,
HC(CO2Et)2), 4.19 (4 H, q, J = 7.2 Hz, 2 × MeCH2OCO),
=
5.55–5.77 (2 H, m, CH CH); dC(50 MHz, CDCl3) 14.00 (2 C),
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8
3 3 7 7

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9 T. A. Blumenkopf and L. E. Overman, Chem. Rev., 1986, 86, 857–873.
10 S. K. Ghosh, R. Singh and G. C. Singh, Eur. J. Org. Chem., 2004,
4141–4147.
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3 3 7 8
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 3 6 9 – 3 3 7 8